Here’s a thumbnail sketch of one Descartes.
This Descartes’s aim, by the end of Meditations, is — as Maddy puts it — to replace the reigning Scholastic Aristotelianism with his own Mechanistic Corpuscularism. For he believes that the then dominant systematic story of the world is in deep error. He has a diagnosis, too, of the source of error — he sees Aristotelianism as springing from some deeply embedded childhood habits of thought. Radical measures are required to prise us out of such deep-rooted error. The ‘Method of Doubt’ provides the once-in-a-lifetime jolt needed to shift us out of certain childish thought-habits and to get us adopt better intellectual methods and open the way to improved science. Faced with even the most reasonable-seeming presumptions,
I must withhold my assent from these former beliefs just as carefully as I would from obvious falsehoods, if I want to discover any certainty in the sciences.
For this Descartes, it is not that our former beliefs are all unreasonable: but we are to play along with fantasies about dreams and evil demons as an instrumental step to help us sort out the safe beliefs from the contaminating dross. And then, as Maddy puts it,
The hope is that once we set aside all our ordinary beliefs, reasonable or not, some absolutely indubitable foundational beliefs will then emerge, on the basis of which science and common sense can then be given a ﬁrm foundation. The Method of Doubt is the one-time expedient that enables us to carry out this difﬁcult task.
So this Descartes’s hope and belief is that, after his strategic retreat, he will still be left with enough indubitable foundational beliefs to provide a secure bridgehead from which he can fight back and recover those common-sense beliefs that don’t carry the baggage of disputable theory, and then go on to ground a secure corpuscularian science.
Is this thumbnail sketch true to the historical René Descartes? For all I know, yes. And Maddy appeals to the work of the Descartes scholar Janet Broughton in support of her reading. But I don’t suppose that — as a Second Philosopher — it matters particularly to Maddy whether the reading does get the real René right. She is after the truth about what there is and how we know it: and getting at those truths about the world is only indirectly aided, if at all, by pursuing the second-order issue of the precise truth about what some relatively remote struggling enquirer happened, with uneven degrees of clarity, to think was the truth about the world.
Let me, by way of aside, say just a bit more about this (speaking here for myself). Why should the philosopher be any more especially interested in the history of her subject than the physicist is in the history of hers? If you take a broadly naturalist line, then I think the answer, to a first approximation, is: there is no good reason. The physicist and philosopher alike should start from the hard-won available theoretical options in their best-developed forms. Of course, philosophy is difficult, there’s a danger of foreclosing options too soon, and it is a good to remind ourselves that there may be more theoretical options than the currently most explored ones: the Great Dead Philosophers might provide a useful source we can mine for alternative ideas. So, less approximately, the naturalistic philosopher — being grateful for all the help she can get in her pursuit of truth — might occasionally delve into the history of philosophy for inspiration (and she supposes that she’s more likely to get inspiration from something like the lines of thought actually pursued by her best predecessors than from straw positions created by incompetent exegesis). Still, by my lights, the naturalistic philosopher’s interest in the history of her subject should remain relatively minor and completely instrumental. It perhaps feeds into her thinking about causation or knowledge, or whatever: but it is causation and knowledge that she cares about, and she is interested in Descartes or Hume or Kant only insofar as they offer useful pointers. And as soon as she finds herself at the edge of interpretative swamps — which is in practice rather soon — the naturalistic philosopher will typically lose interest: let the historians amuse themselves, and come back and tell her if and when they manage to dredge up any new nuggets of wisdom that will actually help her with her present philosophical problems. She’s certainly not holding her breath.
Back though to Maddy’s Descartes. How should the Second Philosopher regard his project? Well,
[She] will agree that many of her childhood beliefs were false, and that the judgments of common sense often need tempering or adjustment in light of further investigation, but she will hardly see these as reasons to suspend her use of the very methods that allowed her to uncover those errors and make the required corrections!
And she isn’t much impressed with Descartes’s assumption that (prior to engaging in the Method of Doubt) we are inevitably stuck in childish ways of thinking. The very existence of modern science seemingly gives the lie to that. So she isn’t at all persuaded that pursuing the project of the Meditations is an essential prolegomenon to getting a successful science. Still, the Cartesian meditator does promise something she agrees would be worth having, i.e. a secure method for science. So, even though the Second Philosopher is now very suspicious about whether his methods are going to deliver, in her open-minded way
she might well think it proper procedure to read past the ﬁrst Meditation, to see what comes next. The unconvincing arguments that follow will quickly conﬁrm her expectation that there is no gain to be found in this direction.
The Second Philosopher, then, sees no reason to follow Descartes steps into the mess he gets himself into. Rather, “she will continue her investigation of the world in her familiar ways, despite her encounter with Descartes and his meditator.” As Maddy puts it,
She will ask traditionally philosophical questions about what there is and how we know it, just as they do, but she will take perception as a mostly reliable guide to the existence of medium-sized physical objects, she will consult her astronomical observations and theories to weigh the existence of black holes, and she will treat questions of knowledge as involving the relations between the world — as she understands it in her physics, chemistry, optics, geology, and so on — and human beings — as she understands them in her physiology, cognitive science, neuroscience, linguistics, and so on.
Which seems to me, I must say, just the right way to go!
But others might complain that the Second Philosopher has rather thumpingly missed the true lesson we should draw from her encounter with Descartes. Whether this is so is the topic of the next section.